Sanding disc



1, 1957 T. A. RUPP 2,807,918

SANDING DISC Filed Aug. 27, 1956 THEODORE A. FeuPP INVENTOR.

BY fbmmjl penters, builders and the like.

United States Patent SANDING DISC Theodore A. Rupp, Woodland Hills, Calif.

Application August 27, 1956, Serial No. 606,255

8 Claims. -(Cl. 51-195) The present invention relates generally to the field of tools and more particularly to anovel and improved sanding disc for use with a power-operated hand sander.

Hand-supported power-operated sanders find wide application among professional and amateur woodworkers, car- These devices generally include a housing wherein is mounted an electric motor. This electric motor rotates a shaft to which is keyed an annular support disc. The support disc is adapted to removably receive a replaceable sanding disc, the face of which .is covered with a layer of abrasive particles. In operation, the 'face of the rotating sanding disc is held against the work to be sanded. Where the surface being sanded is uniplanar and the support disc is maintained parallel thereto, it is possible for a skilled operator to avoid other than minor gouging or scoring of this surface by the peripheral portion of the sanding disc. Where the surface being sanded is irregular and/ or the support disc is not maintained in paralellism with this surface, the peripheral portion of the sanding disc tends to gouge or score this surface. Such irregularities result primarily from the absence of any support for the peripheral portion of the sanding disc radially outwardly of its periphery. Because of this lack of support, the peripheral portion of the sanding disc is free to cut into the surface being sanded once the support member is tilted out of parallelism with this surface. The removal of these irregularities is both time-consuming and tedious.

It is a major object of the present invention to provide a novel and improved sanding disc that will not gouge or score the surface being sanded.

Another object is to provide a sanding disc of the aforedescribed nature which is inexpensive to manufacture and may be sold at substantially the same price as conventional sanding discs.

A more particular object of the invention is to provide a sanding disc having an abrasive-free raised peripheral portion.

These and other objects and advantages of the present invention will become apparent from the following detailed description, when taken in conjunction with the appended drawings, wherein:

Figure 1 is a side elevational view taken partly in central vertical section and showing a first form of sanding disc embodying the present invention;

Figure 2 is a fragmentary top plan view of said disc;

Figure 3 is an enlarged, fragmentary vertical sectional view taken on line 33 of Figure 2;

Figure 4 is an enlarged, fragmentary, vertical sectional view of a second form of sanding disc embodying the present invention;

Figure 5 is an enlarged, fragmentary, vertical sectional view of a third form of sanding disc embodying the present invention;

Figure 6 is an enlarged, fragmentary, vertical sectional view of a fourth form of sanding disc embodying the present invention; and

Figure 7 is an enlarged, fragmentary, vertical sectional 2,807,918 Patented 0a. 1, 1957 view of a fifth form of sanding disc embodying the present invention.

Referring to the drawings and particularly Figures 1, 2 and 3 thereof, the first form of sanding disc S embodying the present invention is shown mounted upon a support disc 10 which is keyed to the rotatable shaft .12 of a conventional power-driven sander D. Thespecifi-c construction of the sander D does not form .a .part of the present invention. The sanding disc S has a front or work-engaging face 14 which is adapted to be held against asurface to be sanded.

The sanding disc S includes a backing disc 16Iformed of cardboard or the like. This backing disc 16 is removably affixed to the support disc 10 as by bolt .18. Theworkengaging face 14 of the backing disc 16 is covered with a layer of abrasive particles 20 with the exception of its peripheral portion. This peripheral portion -is covered by a non-abrasive ring22. The non-abrasive ring 22 may conveniently be formed of the same material as the backing disc 16 and its underside is rigidly a ffixed as by glue to the front of the backing disc 16. As'indicated in Figure '3, the front surface 24 of the ring 22 is raised above the plane of the abrasive particles 20.

In the operation of this form of the device, .the rotating work-engaging face 14- of the sanding disc S is held against a surface to be sanded. Inasmuch as the .nonabrasive ring 22 is thicker than the layer of abrasive particles 20, its front surface 24 will prevent contact of the radially outermost abrasive particles with this surface. Additionally, the non-abrasive ring 22 will provide a support for the radially outer portion of the sanding disc thereby preventing gouging of this surface by the abrasive particles 20. This will be true even though the support disc 10 is not in parallelism with the surface being sanded.

Referring now to Figure 4 there is shown a second form of sanding disc S-2 embodying the present invention. This form of sanding disc S-2 is generally similar to the first form shown in Figures 1, 2 and 3. It includes a cardboard backing disc 30, to the work-engaging face of which is bonded a layer of abrasive particles 20. In this form of sanding disc, however, these abrasive particles extend to the radially outer edge of the backing disc 30. A non-abrasive ring 32 is aflixed to the peripheral portion of the backing disc 30, the underside of this ring 32 being glued or otherwise bonded directly over the outermost abrasive particles 20. The operation of this form of sanding disc is the same as described hereinabove with regard to the first form of sanding disc.

Referring now to Figure 5, there is shown a third form of sanding device S-3 embodying the present invention. In this form the peripheral portion of the cardboard backing disc 40 is doubled-over forwardly so as to define an integral raised non-abrasive ring 42. This doubled-over portion is glued or otherwise bonded to the front of the backing disc 40. The layer of abrasive materials extends to the radially inner edge of the non-abrasive ring 42. It will be observed that the front surface 44 of this non-abrasive ring 42 is raised above the plane of the abrasive particles 20.

Referring now to Figure 6 there is shown a fourth form of sanding disc S-4 embodying the present invention. This form of sanding disc includes a cardboard backing disc 50, the peripheral portion of which is offset forwardly by a cardboard ring 52 disposed thereunder so as to define a non-abrasive ring 56. The abutting surfaces of the ring 52 and the backing disc 50 are glued or otherwise bonded together.

Referring now to Figure 7 there is shown a fifth form S-5 of sanding disc embodying the present invention. This form of sanding disc includes a flat cardboard backing disc 60. The entire surface of this backing ring 60 is covered by a layer of abrasive particles 20. The abrasive particles 20 disposed on the peripheral portion of the disc 60, however, are coated with a synthetic plastic material 62, or the like, so as to provide a non-abrasive ring section 64. This plastic material 62 may be extended over the edge of the backing disc 60 if desired. As indicated in this figure, the front surface of the non-abrasive ring section 64 is substantially flush with the plane of the layer of abrasive particles 20. In the operation of this form of sanding disc, the plastic-coated peripheral portion 64 of the disc serves as a support for the radially outermost uncoated abrasive particles 20 so as to prevent their gouging or scoring the surface being sanded.

Various other modifications and changes may be made with respect to the foregoing description without departing from the spirit of the invention or the scope of the following claims.

I claim:

1. A sanding disc, comprising: a flexible backing disc; abrasive particles disposed upon the work-engaging face of said backing disc; and a non-abrasive peripheral portion formed on said backing disc, said peripheral portion being raised above said backing disc at least the thickness of said abrasive particles.

2. A sanding disc, comprising: a flexible backing disc; abrasive particles disposed upon the work-engaging face of said backing disc; and a non-abrasive peripheral portion formed on said backing disc, said peripheral portion being raised above said backing disc above the plane of said abrasive particles.

3. A sanding disc, comprising: a flexible backing disc; a layer of abrasive particles bonded to the work-engaging face of said backing disc; and a non-abrasive ring covering the peripheral portion of said backing disc, said ring being at least the thickness of said layer of abrasive particles.

4. A sanding disc, comprising: a flexible backing disc; a layer of abrasive particles bonded to the work-engaging face of said backing disc; and a non-abrasive ring covering the peripheral portion of said backing disc, said ring being thicker than said layer of abrasive particles.

5. A sanding disc as set forth in claim 4 wherein the layer of abrasive particles terminates at the radially inner edge of said non-abrasive ring.

6. A sanding disc as set forth in claim 4 wherein the non-abrasive ring is formed by folding over the peripheral portion of said backing disc forwardly.

7. A sanding disc as set forth in claim 4 wherein the non-abrasive ring is formed by ofisetting forwardly the peripheral portion of said backing disc with a separate ring.

8. A sanding disc, comprising: a flexible backing disc; a layer of abrasive particles bonded to the work-engaging face of said backing disc; and a non-abrasive ring covering the peripheral portion of said backing disc, said non-abrasive ring being formed by coating the peripheral portion of said backing disc with a non-abrasive material.

References Cited in the tile of this patent UNITED STATES PATENTS 1,256,978 Causey Feb. 19, 1918 

